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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef NET_BASE_NETWORK_CHANGE_NOTIFIER_WIN_H_
      6 #define NET_BASE_NETWORK_CHANGE_NOTIFIER_WIN_H_
      7 
      8 #include <windows.h>
      9 
     10 #include "base/basictypes.h"
     11 #include "base/compiler_specific.h"
     12 #include "base/memory/scoped_ptr.h"
     13 #include "base/memory/weak_ptr.h"
     14 #include "base/threading/non_thread_safe.h"
     15 #include "base/timer/timer.h"
     16 #include "base/win/object_watcher.h"
     17 #include "net/base/net_export.h"
     18 #include "net/base/network_change_notifier.h"
     19 
     20 namespace net {
     21 
     22 // NetworkChangeNotifierWin inherits from NonThreadSafe, as all its internal
     23 // notification code must be called on the thread it is created and destroyed
     24 // on.  All the NetworkChangeNotifier methods it implements are threadsafe.
     25 class NET_EXPORT_PRIVATE NetworkChangeNotifierWin
     26     : public NetworkChangeNotifier,
     27       public base::win::ObjectWatcher::Delegate,
     28       NON_EXPORTED_BASE(public base::NonThreadSafe) {
     29  public:
     30   NetworkChangeNotifierWin();
     31 
     32   // Begins listening for a single subsequent address change.  If it fails to
     33   // start watching, it retries on a timer.  Must be called only once, on the
     34   // thread |this| was created on.  This cannot be called in the constructor, as
     35   // WatchForAddressChangeInternal is mocked out in unit tests.
     36   // TODO(mmenke): Consider making this function a part of the
     37   //               NetworkChangeNotifier interface, so other subclasses can be
     38   //               unit tested in similar fashion, as needed.
     39   void WatchForAddressChange();
     40 
     41  protected:
     42   virtual ~NetworkChangeNotifierWin();
     43 
     44   // For unit tests only.
     45   bool is_watching() { return is_watching_; }
     46   void set_is_watching(bool is_watching) { is_watching_ = is_watching; }
     47   int sequential_failures() { return sequential_failures_; }
     48 
     49  private:
     50   class DnsConfigServiceThread;
     51   friend class NetworkChangeNotifierWinTest;
     52 
     53   // NetworkChangeNotifier methods:
     54   virtual ConnectionType GetCurrentConnectionType() const OVERRIDE;
     55 
     56   // ObjectWatcher::Delegate methods:
     57   // Must only be called on the thread |this| was created on.
     58   virtual void OnObjectSignaled(HANDLE object) OVERRIDE;
     59 
     60   // Does the actual work to determine the current connection type.
     61   // It is not thread safe, see crbug.com/324913.
     62   ConnectionType RecomputeCurrentConnectionType() const;
     63 
     64   void SetCurrentConnectionType(ConnectionType connection_type);
     65 
     66   // Notifies IP address change observers of a change immediately, and notifies
     67   // network state change observers on a delay.  Must only be called on the
     68   // thread |this| was created on.
     69   void NotifyObservers();
     70 
     71   // Forwards connection type notifications to parent class.
     72   void NotifyParentOfConnectionTypeChange();
     73 
     74   // Tries to start listening for a single subsequent address change.  Returns
     75   // false on failure.  The caller is responsible for updating |is_watching_|.
     76   // Virtual for unit tests.  Must only be called on the thread |this| was
     77   // created on.
     78   virtual bool WatchForAddressChangeInternal();
     79 
     80   static NetworkChangeCalculatorParams NetworkChangeCalculatorParamsWin();
     81 
     82   // All member variables may only be accessed on the thread |this| was created
     83   // on.
     84 
     85   // False when not currently watching for network change events.  This only
     86   // happens on initialization and when WatchForAddressChangeInternal fails and
     87   // there is a pending task to try again.  Needed for safe cleanup.
     88   bool is_watching_;
     89 
     90   base::win::ObjectWatcher addr_watcher_;
     91   OVERLAPPED addr_overlapped_;
     92 
     93   base::OneShotTimer<NetworkChangeNotifierWin> timer_;
     94 
     95   // Number of times WatchForAddressChange has failed in a row.
     96   int sequential_failures_;
     97 
     98   // Used for calling WatchForAddressChange again on failure.
     99   base::WeakPtrFactory<NetworkChangeNotifierWin> weak_factory_;
    100 
    101   // Thread on which we can run DnsConfigService.
    102   scoped_ptr<DnsConfigServiceThread> dns_config_service_thread_;
    103 
    104   mutable base::Lock last_computed_connection_type_lock_;
    105   ConnectionType last_computed_connection_type_;
    106 
    107   // Result of IsOffline() when NotifyObserversOfConnectionTypeChange()
    108   // was last called.
    109   bool last_announced_offline_;
    110   // Number of times polled to check if still offline.
    111   int offline_polls_;
    112 
    113   DISALLOW_COPY_AND_ASSIGN(NetworkChangeNotifierWin);
    114 };
    115 
    116 }  // namespace net
    117 
    118 #endif  // NET_BASE_NETWORK_CHANGE_NOTIFIER_WIN_H_
    119